<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>监听器应用-距离转换器</title>
    <script src="/js/vue.js"></script>
</head>
<body>
    <div id="app"></div>

</body>

<script>
   let vm=new Vue({
      el:'#app',
      data:{
        km: 0,
        m: 0
      },
      methods:{
        kmtom: function(val){
            this.m = this.km * 1000;
        },
        mtokm: function(val){
            this.km = this.m / 1000;
        }
      },
      watch: {
        km: 'kmtom',
        m: 'mtokm'
      }
   })
</script>

</html>